The mildly bitter flavors of baby kale and escarole contrast with the sweetness of roasted winter squash, carrots, and beets. Tangy fig-balsamic dressing and roasted garlic make mellow, low-fat condiments for everything on the platter.
Preheat oven to 425 degrees. Using 2 teaspoons oil, drizzle cut sides of garlic. Wrap each half in foil. Wrap beets in foil. Roast until garlic is soft and beets are tender, 40 to 50 minutes. Leave oven on.
Toss onions with 2 teaspoons oil and 1/4 teaspoon salt. Transfer to a rimmed baking sheet. Toss cauliflower with 2 teaspoons oil and 1/4 teaspoon salt. Transfer to same sheet. Using 1 tablespoon oil, brush or rub carrots and squash. Transfer to a separate rimmed baking sheet.
Roast vegetables, tossing once, until golden brown and tender: 15 to 20 minutes for onions and cauliflower, 20 to 25 minutes for carrots and squash.
Puree figs, vinegar, 2 tablespoons water, a pinch each of salt and pepper, and remaining 2 tablespoons oil in a blender. Rub beets with paper towels to remove skins; cut flesh into wedges.
Arrange greens and roasted vegetables on a platter. Garnish with rosemary. Serve either warm or at room temperature with vinaigrette.